As display devices, there are an organic electroluminescent (EL) display, a liquid crystal display, and the like. The organic EL display generally includes an organic EL panel, a source driver, a gate driver, a control unit, and a power circuit.
The organic EL panel includes a plurality of data signal lines extending in a column direction, a plurality of scan lines extending in a row direction, and a plurality of pixel units arranged at cross-points between the data signal lines and the scan lines. Each of the pixel units includes, for example, a sub-pixel unit PR that emits light for red color (R), a sub-pixel unit PG that emits light for green color (G), and a sub-pixel unit PB that emits light for blue color (B).
Each of the sub-pixel units PR, PG, and PB includes an organic EL element that emits light according to a driving current, a capacitance element that accumulates electrical charge corresponding to a voltage applied to a connected data signal line, and a driving transistor that supplies a driving current corresponding to the electrical charge accumulated in the capacitance element to the organic EL element.
The source driver applies, to the data signal lines, voltages each of which corresponds to a gray-level value of a corresponding display pixel among display pixels included in an image indicated by an image signal. The gate driver applies a voltage to a scan line connected to a selected pixel. The control unit outputs an internal control signal to each of the gate driver, the source driver, and the power circuit to control operation of each of the gate driver, the source driver, and the power circuit. The power circuit supplies a power source voltage corresponding to the specification of the circuit, to each of the constituent elements in the organic EL display.
Patent Literature (PTL) 1 below discloses a display device that reduces power consumption by adjusting a cathode voltage (voltage at an electrode line connected to a cathode electrode in an organic EL element) of an organic EL panel to be closer to a power source voltage VDD.